1. Field of the Invention
Embodiments of the invention generally relate to a method for providing gas to a processing chamber.
2. Background of the Related Art
Integrated circuits have evolved into complex devices that can include millions of transistors, capacitors and resistors on a single chip. The evolution of chip design continually requires faster circuitry and greater circuit density demanding increasingly precise fabrication processes. The precision processing of substrates requires precise control of temperature, rate and pressure in the delivery of fluids used during processing. The control of these fluids is typically facilitated using a gas panel that contains various valves, regulators, flow controllers and the like.
Fluids used during processing are provided to the gas panel and liquid or gas is formed from a central gas source or a supply vessel positioned proximate the panel. Some process gases may be generated at or near the gas panel from a solid material through a sublimation process. Sublimation is generally a process through which a gas is produced directly from a solid at a certain pressure and temperature without passing through a liquid state. Some gases that may be produced through a sublimation process include xenon difluoride, nickel carbonyl, tungsten hexa-carbonyl, and pentakis (dimethylamino) tantalum (PDMAT) among others. As these materials tend to be very active and expensive, careful control of the sublimation process is required in order to manage the generation of the sublimed solid without undue waste.
A conventional sublimation process is typically performed in a heated vessel loaded or filled with a solid precursor material to be sublimed. As gas is needed, the vessel walls and/or tray supporting the solid precursor material are heated and the gas is produced.
An alternative gas generation process includes mixing a solid or liquid precursor material with a liquid. A carrier gas is then bubbled through the mixture to carry the generated process gas.
However, as the carrier gas is bubbled through or impacted against either a solid precursor or liquid/solid mixture, particulates from the solid precursor and or liquid may become entrained in the carrier gas and transferred into the process chamber. Liquid or solid particulates may become a source of chamber or substrate contamination. Thus, reduction of particulates passing from precursor gas generator into a processing chamber would serve at least two purposes. First, such a reduction in particulates would reduce substrate defects. Second, a reduction in particulates would reduce the downtime required for cleaning the contaminated chamber surfaces.
Therefore, there is a need for an improved method and apparatus for providing a precursor gas to a processing chamber.